Neoadjuvant palbociclib and anastrozole (NeoPalAna) is a single-arm phase II clinical trial for patients with stage II/III ER+/HER2- breast cancer. Patients recieved Anastrozole for 4weeks followed by palbociclib. On day 15, patients were biopsied and Ki67% was determined. Patients with Ki67 >10% were deemed resistant to therapy. These biopsies were subsequently frozen for multi-omics processing